Chinese controller burning out with 52v battery

[MattH]

I recently purchased a 1500w ebike conversion kit from RisunMotor on AliExpress: https://www.aliexpress.com/item/32390331389.html?spm=a2g0s.9042311.0.0.74884c4dlFHWpq

For the battery, I went with this 52v 20ah one from another vendor: https://www.aliexpress.com/item/32831029101.html?spm=a2g0s.9042311.0.0.74884c4dlFHWpq

I got everything hooked up and took it for a spin. After about 5 minutes of riding, the screen turned off and I lost power. I noticed that there was now some resistance when rolling the rear wheel (what I assume regenerative braking feels like). I couldn't get it to turn back on so the next logical step was to unplug the battery and plug it back in. When I plugged it back in, it sparked and melted the part of the power connector.

I eventually narrowed the issue down to the controller. My multimeter measures 0 ohms across the power input which didn't seem right... I contacted Risunmotor. They responded right away and sent out a replacement controller for $30 shipping. It arrived less than a week later!

I hooked up the new controller and took the time to program the p and c settings on the screen. Specifically, I made sure to set C5 to 7. Risunmotor recommends 8, but I wanted to be more conservative with my 52v battery. The test ride was a blast. This thing rips up steep hills at 20mph. The screen was reading roughly 1800w at full throttle. After about 15 minutes of riding around with various amounts of throttle, I lost power to the motor. The screen was still on, but the throttle wasn't working anymore.

I took a short break and revisited the c5 setting, this time lowering it to 5. The throttle started working again and I rode around some more. Now the screen reads about 1500w at full throttle and still feels like a powerful ride.

After 5 minutes of this, everything dies again with the same symptoms as my first controller. I unplugged and replugged to a nasty spark, and the controller reads 0 ohms across the power input.

My thoughts are that maybe these Chinese controllers are not hardy enough for a 52v battery? It seems unlikely that I would have gotten 2 similarly defective ones in a row. Do you think a different controller would resolve my issue? Which one? I'm considering ordering one from ebikes.ca, but are there any cheaper options that are tried and true?

Sorry for the long-winded post and thank you for any advice you have!

 

[dogman dan]

Sounds like a lot of watts for your battery too, but its not unheard of for multiple new controllers to just die. I have run through a few, of the cheapo type, and seen others have similar problems.

Try to get the vendor to keep sending new ones.

Back to battery, the thing may be hitting low voltage cut off, if the screen goes dark. I mean the battery bms shuts it down. When it shuts down and the screen stays lit, then starts to run again, thats the controller lvc cutting it off.

 

[MattH]

The screen never went dark until the controller was fried. The battery was fully charged at ~58v. Is it strange that both times the controller itself became a short circuit?

I'm hesitant to keep paying $30 for unreliable controllers. I'd rather just pay more for something that works. Can anyone recommend a cheapo variety that is rated for more power?

I might just end up shelling out for something nice from ebikes.ca, but I'm still not sure which one is appropriate for my situation.

I forgot to include this info in my original post, but my main applications for the bike are commuting to work in Durango, CO and picking up the truck after a mtb shuttle. Both of these require many miles of uphill riding and I'd like to be able to crank the throttle with confidence.

 

[MattH]

Also, I opened up my original controller and don't see any obvious signs of damage.

 

[MadRhino]

Cheap controllers need upgrading when riding them at their power limit for long periods of time. Even then, few will last very long under abuse if they are not built with low resistance mosfets.

Bigger wires and connectors, beefed traces, proper air flow positioning, are making them run cooler. That is minimizing the risk.

 

[Dauntless]

Now that my 6 hour screen freeze is over. . . .

I could only guess at all this, I don't have any of your equipment myself. So I have questions for you to answer, which I believe will reveal all.

Have I found your controller? https://www.aliexpress.com/item/32784167038.html Is that REALLY just a 22a continuous controller? Is your hub more likely to need a 40a continuous controller? Will it claim to be 80-100a when it's good enough to survive with your motor? Do you need this one? https://www.aliexpress.com/item/1005001285662696.html Might it be a good idea to look at a different manufacturer? https://www.aliexpress.com/item/4001047029643.html

Just keep in mind people seem to be happiest upgrading to a controller that sounds way bigger than they need.

(Oh, is that $21.98 shipping they're making you pay $30 for?)